WDX USER INSTRUCTIONS ENGLISH 71576322 06-05
Page 38 of 46
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7 FAULTS; CAUSES AND REMEDIES
FAULT SYMPTOM
Pu mp o v erh eat s an d s eiz e s
B earin g s h av e sh o rt l if e
Pu m p v ib rat es o r is n o i s y
M ech an ic al se al h a s sh o r t lif e
M ech an ic al se al l ea ks ex ce ssiv el y
Pu mp req u ir es ex ces siv e p o wer
Pu mp lo se s p rim e af t er st ar t in g
In su f f icien t p r e ssu r e d ev elo p ed
In su f f icien t c ap ac it y d el iv er ed
Pu mp d o es n o t d e liv er liq u id
PROBABLE C AUSES
POSSIBLE REMEDIES
A. Syst em troubles
Pump not primed.
Pump or suction pi pe not compl etel y filled with
liquid.
Chec k compl ete filling. Vent and/or prime.
Suction lift too high or level too low.
Insufficient margin between s uction pr essure and
vapour press ure.
Chec k NPSH
A
>NPSH
R
, proper submergence,
losses at strainers and fittings.
Exc essi ve amount of air or gas in liquid.
Chec k and purge pipes and s ystem.
Air or vapour poc ket in s uction line.
Chec k suc tion line design for vapour poc kets.
Air leaks into suc tion line.
Chec k suc tion pipe is airtight.
Air leaks into pump through mechanical s eal,
sleeve j oints, c asing joint or pi pe plugs.
Chec k and r eplac e faulty parts.
CONSULT FLOWSERVE.
Foot valve too s mall.
Investigate repl acing the foot val ve.
Foot valve partiall y clogged.
Clean foot val ve.
Inlet of s uction pipe ins ufficientl y submerged.
Chec k out s ystem design.
Speed too l ow.
CONSULT FLOWSERVE.
Speed too high.
CONSULT FLOWSERVE.
Total head of s ystem higher than differenti al head
of pump.
Total head of s ystem l ower than pump design
head.
Chec k s ystem l osses.
Remedy or CONSU LT FLOWSERVE.
Specific gravity of liquid differ ent from design.
Viscosity of liquid differs from that for which
designed.
Chec k and CON SULT F LOWSERVE.
Operati on at very low capacity.
Measure value and c hec k mini mum permitted.
Remedy or CONSU LT FLOWSERVE.
Operati on at high capacity.
Measure value and c hec k maximum per mitted.
Remedy or CONSU LT FLOWSERVE.
B. Mechanical troubles
Misalignment due to pipe str ain.
Chec k the fl ange c onnecti ons and elimi nate strai ns
using elastic c ouplings or a method permitted.
Improperl y designed foundati on.
Chec k setting of bas epl ate: tighten, adjus t, grout
base as required.
Shaft bent.
Chec k shaft runouts are within acc eptable values.
CONSULT FLOWSERVE.
